ABSTRACT

Sandstone and carbonate rocks in the deep Anadarko Basin show deformation features induced solely by the increased pressures and temperatures of deep burial. The rocks are at temperatures around 210°C and an overburden pressure of about 2.5 kb.

Mean vitrinite reflectance (R_o) values from the Lone Star Bertha Rogers well were plotted versus depth as a means of developing a ranking parameter to characterize the thermal history of the deep Anadarko Basin. Temperatures of 200°C and higher had no apparent effect on the development of diagenetic textures or formation of new minerals, even though these temperatures approach those found in the zone of greenschist facies metamorphism.

Large calcite crystals in the limestones show extensive twin development accompanied by bending or multiple displacement along twin lamellae. Inferred granulation or cataclastic textures are shown by large calcite crystals which are now bordered by small anhedral calcite grains, a product of mechanical breakage. Pressure-solution features are common and aggrading recrystallization has led to an increase in average crystal size with depth.

Limestones at these depths are tight compared to dolostones in the same basin at slightly shallower depths. These dolostones still retain in excess of 20% porosity at about 26,000 ft.

Among sandstones of the Simpson Group only the development of concavo-convex and sutured boundaries and undulose extinction of quartz grains can be directly related to stresses and strains developed during deep burial.

Mechanical adjustment occluded pores. Both limestones and sandstones are tight.